1. Field of the Invention
This invention pertains to scaffolds, and more particularly to collapsible scaffolds having vertically adjustable work platforms.
2. Description of the Prior Art
Various equipment has been developed to vertically adjust the height at which workmen perform their tasks. For example, Bulletin MS-55, published by the Morgen Mfg. Co., Yankton, S.D., illustrates tower scaffolding suitable for supporting masons building high walls. While the Morgen scaffolding has enjoyed some success, it possess two deficiencies. The first is that the individual scaffold towers are not self standing because each tower is supported by a base having only two legs. Consequently, a workman or other means is required merely to hold a first tower while additional towers are being erected. Secondly, there is no fail safe safety device for securely locking the platforms to the towers.
U.S. Pat. No. 2,140,617 shows a vertically adjustable scaffold that includes a standard supported by a tripod of three braces, thus making the standard self standing. In one version of the scaffold, the three braces are independently adjustable relative to each other. However, the braces are not collapsible with respect to the standards, thereby rendering the standards bulky and cumbersome to store.
U.S. Pat. No. 3,480,110 illustrates an extendible scaffold having a three legged support base for each upright member. One of the legs is pivotable about the upright member, while the two other legs remain rigidly fastened to the upright member. In the collapsed condition, the pivotable leg remains skewed relative to the fixed base legs, so the support base is awkward to handle and store.
Thus, a need exists for a self standing scaffold with a base that is collapsible for easy storing and transporting and that has a fail safe device for supporting the workers' platform.